Officially from IBO, pseudocode and flowchart:

OOP: object-oriented programming
PPT : Powerpoints for OOP
Open book references: Chapter 15
http://openbookproject.net/thinkcs/python/english3e/classes_and_objects_I.html
Chapter 16:
http://openbookproject.net/thinkcs/python/english3e/classes_and_objects_II.html